Rock drill



J. C. CURTIS 'ROCK DRILL Dec. 17, 1940.

Filed July 8, 1937 3 Sheets-Sheet l C. CURTIS Dec. 17, 194-0.

ROCK DRILL Filed July 8, 1957 3 Sheets- Sheet I5 Jizvenfir: Z @7212 a 6'-1 4' Wm.

Patented Dec. 17, 1940 l UNITED STATES PATENT QFFICE ROCK DRILL JohnClark Curtis, Claremont, N..H.,- assignor to SullivanMachineryCompany, acorporation of Massachusetts Application July 8, 1937, Serial N 0.152,609

33 Claims. (01. 12119.)

This invention relates to rock drills, and more substantially on line 22of Fig. 1, the drill particularly, but not exclusively, to a rock drillhammer motor being partially shown in end of the pressure fluidactuated, hammer type elevation.

having improved fluid distribution means for the Fig. 3 is an enlargedcross sectional view taken hammer motor. substantially on line 3-3 ofFig. 1. J 5

An object of this invention is to provide a rock Fig; 4 is an enlargedcross sectional view taken drill of an improved design wherein theefficiency substantially on line 4-4 of Fig. 1. is greatly improved andthe component parts Fig. 5 is a rear end elevational view of the frontare made relatively rugged and durable in convalve element.

struction. Another object is to provide, in arock Fig. 6 is' a front endelevational view of the 10 drill of the hammer type, improved fluiddistrirear valve element. bution means for the drill hammer motor where-Fig. '7 is an enlarged fragmentary sectional by pressure fluid isdistributed to the motor view taken in the plane of Fig. 1, showingdecylinder in a novel and improved manner; A tails of the improved fluiddistribution means.

further object is to provide an. improved fluid Figs. 8 and 9 are viewssimilar to Fig. '7 show- 15 distribution means having improved fluiddising the valve elements and hammer piston in tributing valve mechanismand flow passage ardifferent positions.

rangements whereby the motive fluid is dis- Fig, 10is a cross sectionalview taken substantributed to the motor cylinder in an improved tiallyOn li e |n|0 O manner. Another object is to provide an im- Fig. 11 is across sectional view taken substan- 20 proved valve mechanism of themulti-valve type tially on line I |-l I of Fig. '7. embodying a pair ofcooperating, relatively mov-' Fig. 12 is a developed view inlongitudinal secable, valve elements for controllingthe flow tion takensubstantially on line l2l2 of Fig. 10, of pressure fluid to the motorcylinder in an showing certain of the fluid distributing passagesimproved manner. A further object is to proandthe'valve throwingpassage. 25 vide, in a valve mechanism of the above char- Fig. 13' is across sectional view taken substanacter, an improved flow passagearrangement tially on line l3'-I3 of Fig. '7'. associated with the valveelements together with Fig. 14 is a detail sectional view taken on linea novel throwing means for the valve elements I4I4 of Fig. 2.

whereby the speed of operation and efiiciency Fig. 15 is a detailsectional view taken on line 30 of the drill hammer motor are greatlyimproved. l5|5 of Fig. 2.

Still another object is to provide, in a valve Fig. 16 is an enlargedfragmentary sectional mechanism of the above character, an improved Viewtaken in the plane of Fig. 8, showing the valve construction andassociated flow passage distributing valves both in seated position.

rrangement whereby the hammer piston of the In the illustrativeembodiment of the inven- 35 hammer motorv is actuatedv to deliver anextion, there is shown a pressure-fiuid-actuated, fremely powerful blowto the drill steel, the valve hammer rock drill of the mounted driftertype, elements of the improved valve structure being although it will beevident that various features arranged in a novel manner so that fluidis dis- 0f the invention may be embodied in rock drills tributed to themotor cylinder to cause the hamof various. other types; 40 mer piston tostrike an unimpeded, uncushioned I In this construction, the referencecharacter I blow on the drill shank, while, at the same time, generallydesignates the drill hammer motor, the consumption of pressure fluid isreduced to a 2 the guide shall, 3 the feeding means for the minimum.These and other objects and adhammer motor, 4 the chuck mechanism and 5the 5 vantages of the invention will, however, herein improved throttlevalve mechanism. The motor after more fully appear. cylinder 6 haslateral guides 1, 1 slidably re- In the accompanying drawings there isshown ceived in longitudinal guideways 8, 8 formed on for purposes ofillustration one form which the the guide shell 2, and the latter has abottom invention, in its various aspects, may assume in trunnion support9 adapted to be; clamped in practice. the usual saddle mounting of atripod or column. 50

In these drawings- I The feeding means 3 comprises a feed screw l0 Fig.1 is'a view in longitudinal vertical section journaled at its oppositeends within bearing through a rock drill incorporating an illustrativeyokes II. I l secured to the opposite ends of the embodiment of theinvention. guide shell and having at its rear end a manual Fig. 2 is anenlarged cross sectional view taken rotating handle !2. The feed screwthreadedly 55 engages a non-rotatable feed nut l3 fixed within the boreof a depending boss l4 formed integral with the motor cylinder 6. As thefeed screw is rotated by the handle l2 relative to the nonrotatable feednut, the drill hammer motor is fed either forwardly or rearwardly alongthe shell guideways, depending upon the direction of feed screwrotation. As the guide shell 2 and feeding means 3 are of a conventionaldesign, further detailed description thereof is unnecessary.

Now referring to the improved hammer motor I, it will be noted that themotor cylinder has a piston chamber or bore l5 containing areciprocatory hammer piston l6 having a piston head I! fitting thecylinder bore and a forwardly projecting striking bar l8 adapted todeliver impact blows to the shank of a usual drill steel [9. The pistonstriking bar is guided in a bore 20 formed in a front buffer ring 2!having an external flange 22 at its rearward end fitting the forward endof the cylinder bore to provide a front cylinder head. This buffer ringhas a portion 23 fitting in a bore 24 in the front cylinder extension25, and has an external flange 26 abutting the front end f the cylinderextension, in the manner clearly lhOWll in Fig. 1. The buffer ringextension has a bore 21 providing an elongated bearing for a chucksleeve 28 rotatably mounted at its forward nd within a chuck housing 29.This chuck busing abuts the forward face of the flange 26 and has a borereceiving the forward portion of the buffer ring extension 23. Within abore 30 formed in the chuck sleeve is a chuck bushing 3| itting aninwardly directed shoulder 3 I on the Ihuck sleeve and having a bore forreceiving the h n: of the drill steel. The chuck bushing is held inposition within the chuck sleeve by means of a combined driver andlocking member 32 hreaded at 33 within the forward portion of the cksleeve. The chuck housing has an inard y directed flange 34 providing ashoulder ainst which the forward end of the chuck sleeve abuts, and thisflange provides an axial ening through which the forward portion of hemember 32 extends. Upon unscrewing of the member 32 from the chucksleeve, this member may be withdrawn forwardly from the chuck housing toobtain access to the chuck bushing for replacement purposes. Forwardrelease of the member 32 from the chuck housing is also desirable in theevent of the lugs and the rear end of the drill shank becoming headedover or distorted due to the repeated impacts thereon, preventingwithdrawal of the steel shank from the chuck bushing and the lockingmember. The chuck sleeve is formed with an external flange 35 arrangedbetween the forward end of the buifer ring extension 23 and a shoulder36 formed within the chuck housing. The chuck housing and the bufferring extension provide elongated bearings for the chuck sleeve so thatthe latter is maintained in proper alinement with the cylinder. Thedriver and locking member 32, as shown in Fig. 4, has internal drivinglugs 31 engageable with lugs 38 on the drill steel shank, and is formedwith a key opening 39 for receiving the steel shank lugs. When the lugson the steel shank are inserted through the key opening within thedriver member and the steel is turned to bring the shank lugs 38 intodriving engagement with the lugs 31, the shank lugs are brought out ofregistry with the key opening so that the steel shank is locked againstforward displacement from within the driver member. Pressed in a bore 40formed within the rearward portion of the chuck sleeve is a chuck nut 4|held against rotation relative to the chuck sleeve by means of a key pin42 fitted in registering grooves on the chuck sleeve and chuck nut. Whenthe chuck sleeve is removed from within the buffer ring extension bore,the chuck nut may be withdrawn axially through the rear end of the chucksleeve for replacement purposes.

As is usual in rock drills of the type disclosed, means is providedfor-rotating the drill steel as it is percussively actuated by thehammer piston, comprising a rotatable pawl carrier 43 carrying usualspring-pressed pawls engageable with the teeth of a non-rotatableratchet ring 44. Formed integral with the pawl carrier is a rifle bar 45having spiral grooves slidably interlocked with spiral keys formed on arifle nut 46 fixed within the hammer piston. As the hammer piston movesforwardly to effect its working stroke, i. e., to deliver an impact blowto the shank of the drill steel, the pawls of the pawl carrier slip overthe ratchet teeth so that the hammer piston delivers an unimpeded blowto the steel shank. During the return stroke of the hammer piston, thepawls on the pawl carrier engage the ratchet teeth to hold the rifle baragainst rotation, and, as a result, the hammer piston is rotated. Therotary motion of the hammer piston is transmitted to the drill steelshank through straight grooves 41 on the piston striking bar slidinglyinterlocked with straight keys on the chuck nut 4|, rotating the latterwith the piston, and, as a result, effecting rotation of the chucksleeve, chuck bushing and driver member, and hence the drill steel islocked within the driver member. It will thus be seen that as the drillsteel is percussively actuated by the hammer piston, it isintermittently rotated, in the manner well understood by those skilledin the art.

The improved fluid distribution means will now be described. Formed in arearward extension of the motor cylinder is a bore 50 arranged in axialalinement with the motor cylinder bore, and arranged in this extensionbore is a valve seat plate 5| constituting the rear cylinder head andhaving a sleeve-like portion 52 projecting axially from its rear face,the latter providing a bearing for the rifle bar 45. Also arranged inthe extension bore 50 and abutting the rear face of the plate 5| is avalve box 53 having a bore 54 of a uniform diameter throughout itslength. The plate 5| forms a front closure for the bore of the valve box53 while the rear end of the bore is closed by a valve box cover 55likewise arranged in the extension bore and abutting the rear face ofthe valve box 53. Arranged within the rearward portion of the extensionbore 50, behind the ring 44, is a ratchet collar 56. The collar, ratchetring and cover are maintained against rotative movement within the bore50 by a dowel pin or key 51 fitted in registering grooves in thecooperating parts and in the cylinder member 6. Engaging the ratchetcollar is a back head 58 adapted to be clamped to the rear end of thecylinder to hold the parts above described within the extension bore,and the front chuck housing is also clamped to the front end of thecylinder to hold the buffer ring and chuck sleeve in position. The backhead and the front chuck housing are secured to the cylinder in anyappropriate manner, as by usual side rods 59, 59 (Figs. 3, 10, 11 and13).

Referring more particularly to the specific valve structure, it will beobserved that reciprocably mounted in the bore 54 of the valve box is apair of cooperating, relatively movable, fluid distributing valveelements 69 and GI, herein preferably of the sleeve type arranged intelescopic relation and respectively controlling the flow of pressurefluid to the opposite ends of the cylinder bore, in the manner to belater more fully explained. The rear valve element controls admissionand cut-oil for the front end of the cylinder, the front valve elementlike functions for the rear end of the motor cylinder. The rear valveelement 69 comprises a rearwardly located external flange 62 fitting thevalve box bore, and a forwardly projecting sleeve-like body portion 63,telescoping over the rearwardly-extending sleeve-like body portion 64 ofthe front valve element 9 I. Formed on the rear valve element is aninwardly directed internal flange 65 cooperating with a forwardlyprojecting annular portion 66 integral with the valve box cover 55, tometer motive fluid for the front end of the cylinder. The front valveelement has a similar inwardly directed internal flange 61 cooperatingwith the sleeve-like projection 52 integral with the valve seat plate 5|to meter the motive fluid for the rear end of the motor cylinder.function will be later more fully described. Fitting the valve box boreand formed at the front end of the front valve 6| is an external flange68. The opposite end faces of the valves 69 and 6| are formed withannular seating portions 69 and I9 respectively, the former adapted toseat against the front face of the valve box cover 55 and the latter toseat against the rear face of the plate 5|. The front faceof the cover55 is formed with an annular recess II communicating with the valvereceiving bore at the rear side of the valve flange 62 and this recessis connected through a pair of ports 12, 12 in the cover 55 with ports13, I3, and these latter in turn communicate with passages I4, I4 formedin the cylinder (Fig. 12) and communicating through ports 15 with theforward end of the cylinder bore. The rear face of the plate 5| isformed with an annular recess I6 communicating with the valve receivingbore at the forward side of the valve 9|, and this recess is connectedby a series of passages T! with the rear end of the cylinder bore.Formed externally on the valve'box 53 is an annular groove 18communicating through a port 19 with the space between the valves 69 andBI, and this groove is connected, as shown in Fig. 12, by a port 89 witha throwing passage 8|, the latter in turn communicating through ports 82and 83 with the cylinder bore at points spaced longitudinally of thelatter. 4 v

The means for supplying pressure fluid to the valve box bore comprises athrottle valve 84 forming a part of the throttle valve mechanism 5. Thisthrottle valve is arranged within a transverse bore 85 formed in theback head 58. The throttle valve is provided with an internal pressurechamber 86 connectible through a port 9'! with a port 88 formed in theback head and communicating with a pressure chamber 89 formed betweenthe ratchet collar 56 and the back head. This pressurechamber 89 isconnected through a series'of ports 99 with an annular recess 9| formedin the forward face of the ratchet collar 56, and this recesscommunicates through the spaces between the ratchet teeth and pawlcarrier with an annular recess 92 formed in the rear face of the valvebox cover 55. The recess 92 is connected through a series of ports 93with a large axial passage 94 extending through the annular projection66 on the valve box cover and communicating with the internal space Thismetering within the valve elements 69 and 6|. As above indicated,pressure fluid may flow from within the space between the valveelements, past restricted clearance spaces and 96 at the inner edges ofthe internallvalve flanges 65 and 61 respectively, to provide meteringof the fluid flowing past these internal valve flanges so that the flowof pressure fluid to the supply passages is always maintained constantirrespective of any wear of the valves, the valves being guided solelyat the exterior peripheries of the external flanges thereof whichslidingly fit the valve box bore 54. Formed within the wall of thecylinder bore substantially midway between the ends of the cylinder isan annular exhaust groove 91 connected directly to atmosphere through alateral exhaust port 98 (see Fig. 11). between the points ofcommunication of the ports 92 and 93 with the cylinder bore. The valvechamber at the front side of the front valve element 6| is connected tothe rear end of the cylinder bore through a restricted leak passage 99,while the recess II is connected to the recess 92 by a restricted leakpassage I99.

Now referring again to the improved throttle valve structure, it will benoted that the throttle valve is of cylindric form, as shown in Fig. 2,and is provided with a valve stem I92 projecting outwardly through abore I93 formed in the back head. Fitted on this valve stem is a handlehub I 94 having a lateral boss I95 in which is suitably threaded at I96a valve operating handle I91. This valve handle has a tapered inner endI98 adapted to seat within a tapered socket I99 formed within the valvestem. When the handle E91 is unscrewed from within the handle hub bossI95 so that the tapered portion I98 thereof is released from the socketI99, the handle hub I94 may be readily removed from the valve stem. Whenthe parts are in the assembled relation shown in Fig. 14, the handleserves the dual purpose of providing an operating member for the valveand securing means for the handle hub. Pressure fluid is adapted to besupplied to the hollow interior 86 of the throttle valve through Thisexhaust groove lies a usual supply connection II 9 and when this supplyconnection is released from the back head and the handle is removed fromthe valve stem, the throttle valve may be withdrawn axially from itsbore within the back head, in an obvious manner. For holding thethrottle valve 'in its different positions ofadjustment, aspring-pressed plunger III (see Fig. 15) guided in a bore in the backhead is engageable with notches in the valve. v

As is usual in rock drills of the type disclosed, a cleansing liquid isadapted to be conducted through the drill steel to the bottom of thedrill hole to clear the cuttings away from the cutting end of the drillsteel, and this cleansing means herein comprises a conventional liquidconducting tube 2 secured by a packed gland plug H3 within the back head58, and this tube extends axially through bores formed in the rifle barand hammer piston into the bore of the drill steel in a Well knownmanner. Liquid under pressure is adapted to be supplied to the liquidconducting tube from .any suitable source. As liquid is conducted to thebore of the drill steel, fluid under pressure is commingled therewith,thepressure fluid flowing from the cylinder bore past the piston or fromany other suitable pressure fluid source through the bore within thechuck sleeve to the drill steel bore. The liquid and pressure fluidcommlngle as they flow axially through the drill steel to the bottom ofthe drill hole.

The mode of operation of the improved fluid distribution means will beclearly apparent from the description given. When the parts are in theposition shown in Fig. 7, pressure fluid may flow from the interior ofthe throttle valve 84 through ports El, 88, chamber 89, ports 90, recess9|, through the spaces between the teeth of the ratchet ring, groove 92,ports 93 and the axial passage 94 to the internal chamber within thevalve elements. Pressure fluid flows through the restricted clearancespace 95 between the inner peripheral edge of the internal flange 65 onthe rear valve element .and the exterior peripheral surface of theannular projection 66, through the valve box bore past the rear face ofthe rear valve element and through the annular recess 1 I, ports f2, 73,passages 14 and ports 15 to the forward end of the cylinder bore at thefront side of the piston head, the pressure fluid acting on the frontpressure area of the hammer piston to drive the latter rearwardly toeffect its return stroke. The rear end of the cylinder bore is, at thistime, connected to exhaust through the exhaust groove 97 and exhaustpassage 98. As the hammer piston moves rearwardly, the leading(rearward) edge of the piston head overruns the exhaust groove 9?,cutting off communication of the rear end of the cylinder bore with theexhaust, and upon continued rearward movement of the hammer piston, therearward end of the piston head covers the port 82 and the forward endof the piston head uncovers the port 83, and pressure fluid then flowsfrom the front end of the cylinder bore through the port 83, throwingpassage 8! and port 88, through the annular groove 18 and port 19, intothe annular space between the valve flanges 52 and 68, and the pressurein said annular space immediately throws the rear valve element 50rearwardly from its position shown in Fig. '7 to its position shown inFig. 8, causing the annular seating portion 69 on the valve element 69to seat against the front face of the valve box cover 55 and shut offflow of pressure fluid to the forward end of the cylinder bore. Thispressure in the space between the valve flanges also acts to hold theforward valve in closed position. 'Accordingly, the piston continues tomove rearwardly, and as it moves towards the rear cylinder head thepressure fluid trapped within the rear end of the cylinder bore iscompressed, and when the front edge of the piston head uncovers theexhaust groove 9! the pressure within the space between the flanges 62and 68 will be vented to exhaust through passage 19, groove 18, port 80,passage 8|, port 83, and the cylinder bore, while the valve bore at therear side of the rear valve element 60 is connected to exhaust throughthe passages 14, and, as a result, the compression pressure built up bythe piston within the rear end of the cylinder bore acting on the frontpressure area of the front valve element BI is effective to throw thisvalve element rearwardly from the position shown in Fig. 8 to theposition shown in Fig. 9. When the parts arein the position shown inFig. 9, pressure fluid may flow from the internal chamber within thevalve elements 60, 6|, through the restricted clearance space 96 betweenthe inner peripheral edge of the internal valve flange 61 and theexterior periphery of the sleeve 52, through the valve bore at theforward side of the front valve element BI and through the annularrecess 76 and ports 11 to the rear end of the cylinder bore at the rearside of the hammer piston. At this time the front end of the cylinderbore is connected to exhaust through the exhaust groove 91 and exhaustpassage 98, as previously explained.

The pressure fluid acting on the rear pressure area of the hammer pistonnow moves the latter forwardly to effect its working stroke, i. e., todeliver an impact blow to the shank of the drill steel. As the hammerpiston moves forwardly, the forward edge of the piston head first coversthe exhaust groove 91, cutting off communication of the forward end ofthe cylinder bore with exhaust, and upon continued forward movement ofthe hammer piston, the forward end of the piston head covers the port 83and the rearward edge of the piston head thereafter uncovers the port 82of the throwing passage 8|, thereby admitting pressure fluid from thespace at the rear of the piston through the groove 18 and port 19 to thespace between the flanges 62 and '58 of the valves. Due to therestriction at 95 between the internal pressure chamber within the valveelements and the valve receiving bore at the forward side of theinternal valve flange 61, and the relatively rapid flow of pressurefluid from the front end of the valve bore to the rear end of thecylinder bore through the ports 11, the pressure of the fluid at therear of the internal valve flange B! is substantially greater than thatin the valve bore at the front side of the flange. As a result, when thehammer piston reaches the position shown in Fig. 8, and pressure atcylinder pressure admitted through port 82, passage 8!, etc. enters thespace between the valve flanges, the pressure of the fluid within thespace between the external valve flanges and the pressure of the fluidat the rear side of the valve flange B1 overcomes the pressure of thefluid at the forward side of the front valve element 6|, therebythrowing the front valve element from the position shown in Fig. 9forwardly to the position shown in Fig. 8. At this time, the annularseating portions 69 and HI on the remote faces of the valves are bothmomentarily held seated against the end surfaces of the valve bore andthe supply of pressure fluid to the opposite ends of the cylinder boreis completely out off (see Figs. 8 and 16) Forward movement of thehammer piston continues under the expansive action of the pressure fluidwithin the rear end of the cylinder bore. When the forward end of theforwardly moving hammer piston overruns the exhaust groove 91, acompression pressure starts to build up at the forward side of thepiston since the fluid within the forward end of the-cylinder can notescape. The compression pressure continues to build up with the forwardmovement of the hammer piston, but not to a value sufficient to move thevalve element 60 from its seat against the pressure between the externalvalve flanges, until after the port 82 is connected to exhaust as aresult of the pistons uncovering the exhaust groove 91. When the rearend of the piston head commences to uncover the exhaust groove -91,however, release for the rear end of the cylinder will occur andconcurrently, the pressure which has been acting in the annular spacebetween the external flanges on the valves will be vented to the exhaustthrough the passage 8! and port 82; and the compression pressuretransmitted from the front end of the cylinder to the rearward surfaceof the external flange 62 on the rear of the valve 60, through the portI5, passage 14, and

ports 13 and 12, will cause the rear valve to move to the position ofFig. 7 and admit fluid for the rearward traverse of the motor piston.

It will be evident, however, that the motor piston will substantiallycomplete its full working stroke before any motive fluid is admitted tothe forward side thereof, andv accordingly a largely unimpeded blow willbe struck the shank of the drill steel-a much less impeded blow thanwould be possible with any construction utilizing a single valve, suchconstructions permitting but little time between cut-off at the rear endof the cylinder .and admission to the forward end of the cylinder.

The further operation of the motor will consist of repetitions of thecycles which have been described.

It will be noted that throwing of the valve which controls the supply ofpressure fluid to a given cylinder end is effected in an openingdirecticn by compression pressure, upon the venting of the pressure fromthe annular space between the external flangesupon the two valves, andthat the opposite movement of such valve is effected by pressureadmitted between such valve flanges from the cylinder bore, suchopposite movement facilitated by the fact that the relatively free flowto the cylinder from the spaces beyond the restricted annular passagesbounded exteriorly by the internal valve flanges results in less strongpressures holding the valves in open position than would exist were therestriction of flow, so to speak, not provided by these flanges.

The functions of the passages 99 and I00 will be readily understood. Thepassage 99 will admit pressure from the space inside the valves, shouldboth of these valves be closed and the piston be at the rear end of thecylinder, into the restricted space to the rear of the piston, and thispressure will pass back through the port 11 and groove l6 and act on theforward side of the flange 68, and accordingly, the forward valve willbe moved to open position and the motor will then begin to operate in anormal manner.

In the case of the passage Hlll, if the piston happens to be at theforwardend of the cylinder and both valves closed when air is turned on,the pressure will pass through the passage Hill and act upon therearward surface of the flange 62 and movethe rearward valve 60 intoopen position and cause the motor to start. In the normal operation ofthe motor, the passages st and Hill play no material part, as they areso small that their effect upon the operating cycle is negligible.

As a result of this invention, it will be noted that by reason of theimproved valve mechanism and passage arrangement, a, relatively powerfuland eflicient hammer motor is attained. It will further be evident thatby providing cooperating, relatively movable, fluid distributing valveelements respectively controlling the flow of pressure fluid to theopposite ends of the cylinder bore and both capable of being closed atthe same time for a substantial portion of the working piston stroke, itis possible greatly to increase the efficiency of the motor, while atthe same time a more powerful blow is imparted to the drill steel shank,this, in part, being made possible by effecting simultaneous momentaryclosure of the supply passages to the opposite ends of the cylinderbore, thereby permitting the hammer piston to strike a largely unimpededor uncushioned blow to the drill steel shank. It will still further beevident that by the particular hammer motor structure and the improvedarrangement of the parts, a rock drill is provided which is not onlyextremely efiicient in operation but which is also relatively rugged anddurable in construction, well adapted to meet the severe demands ofservice in the drilling of rock. Other uses and advantages of theimproved rock drill will be clearly apparent to those skilled in theart.

While there is in this application specifically described one form whichthe invention may assume in practice, it will be understood that thisform of the same is shown for purposes of illustration and that theinvention may be modified and embodied in various-other forms withoutdeparting from its spirit or the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent is:

1. In a pressure fluid motor, in combination, a cylinder having a bore,a piston reciprocable in said cylinder bore, and fluid distributionmeans for supplying pressure fluid to and exhausting fluid from saidcylinder bore for eifecting reciprocation of said piston comprisingmeans providing a valve chamber, passage means providing fluid supplypassages for connecting the opposite ends of said valve chamber with theopposite ends of said cylinder bore, and a pair of cooperating,relatively movable, fluid distributing valves arranged in slidingtelescopic relation and movably mounted in said valve chamber forrespectively controlling said supply passages.

2. Ina pressure fluid motor, in combination, a cylinder. having a bore,.a piston reciprocable in said cylinder bore, and fluid distributionmeans for supplying pressure fluid to and exhausting fluid from saidcylinder bore for effecting reciprocation of said piston comprisingmeans providing a valve chamber, cooperating, relatively movable, fluiddistributing valves reciprocably mounted in said valve chamber, saidvalves always engaging one another and cooperating to provide a spacetherebetween, means forming passages leading from said valve chamber tothe opposite ends of said cylinder 'bore'at the opposite sides of saidpiston, said passages controlled by said valves respectively'forconducting presure fluid from said valve chamber to the cylinder bore,and throwing passage means communicating with the cylinder bore andcontrolled by said piston for conducting throwing pressure to said spacebetween said valves.

3. In a pressure fluid motor, in combination, a cylinder having a bore,a piston reciprocable in said cylinder bore, and fluid distributionmeans for supplying pressure fluid to and exhausting fluid from saidcylinder bore for'efiecting reciprocation of said piston comprisingmeans providing a valve chamber, cooperating, relatively movable, fluiddistributing valves movably mounted in said valve chamber and havingpressure areas adapted to be subjected to valve throwing pressure, saidvalves cooperating to provide an internal pressure chamber therein,means for constantly supplying pressure fluid to said internal pressurechamber, means forming passages leading from the opposite ends of saidvalve chamber to the opposite ends of said cylinder bore for conductingpressure fluid from said valve chamber to said cylinder bore, saidpassages controlled by said valves respectively, the pressure fluidflowing froms'aid internal pressure chamber past the opposite ends ofsaid valves to said supply passages,

and valve throwing means controlled by said piston for conductingpressure fluid from said cylinder bore to pressure areas on said valvesfor throwing the latter into their different operating positions.

4. In combination, in a motor, a cylinder, a piston reciprocable in saidcylinder, and fluid distribution means for said motor including a valvechest, passages leading from said valve chest to the opposite ends ofsaid cylinder, a pair of valve elements arranged within said valve chestand movable relative to each other and to said valve chest and havingmeans cooperating with said valve chest in one position of said valveelements to provide internally of the valve elements a chamber sealedfrom communication with said cylinder through said passages, and meansfor delivering motive fluid to said chamber for distribution therefromunder the control of said valve elements through said passages to theopposite ends of said motor cylinder.

5. In combination, in a motor, a cylinder, a piston reciprocable in saidcylinder, and fluid distribution means for said motor including a valvechest, passages leading from said valve chest to the opposite ends ofsaid cylinder, a pair of valve elements arranged in said valve chest andmovable relative to each other and to said valve chest, an internalfluid supply chamber arranged within said valve elements, said valveelements controlling the flow of pressure fluid from said internal fluidsupply chamber to said passages, and means for effecting throwing ofsaid valve elements including surfaces on each of said elementscooperating in the formation of a chamher to which fluid is delivered toeffect valve closure and means under the control of said piston fordelivering fluid to and venting fluid from said last mentioned chamber.

6. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, fluid distributing valves arranged in said valvechamber, said valves each having an external flange slidingly fitting aportion of the valve chamber, means for effecting movement of saidvalves relative to one another into their different normal operatingpositions in said valve chamber including means for subjecting the inneradjacent sides of said valve flanges directly to a valve throwingpressure, and means providing fluid supply passages communicating withthe ends of said valve chamber directly at the remote sides of saidvalve flanges respectively for conducting pressure fluid to the oppositeends of said cylinder bore, said valves respectively controlling theflow of pressure fluid through the opposite ends of said valve chamberpast the remote sides of said valve flanges to said supply passages.

7. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, cooperating, relativelymovable, fluid distributing valves arranged in said valve chamber, saidvalves each having a sleeve-like body portion, said body portionsarranged in telescopic sliding relation and each valve having an annularflange formed externally on the sleeve-like body portion thereof, saidvalve flanges slidingly fitting portions of the valve chamber, means foreffecting movement of said valves relative to one another into theirdifferent normal operating positions in said valve chamber includingmeans for subjecting the inner adjacent sides of said valve flangesdirectly to a valve throwing pressure, and means providing fluid supplypassages communicating with the ends of said valve chamber directly atthe remote sides of said valve flanges respectively for conductingpressure fluid to the opposite ends of said cylinder bore, said valvesrespectively controlling the flow of pressure fluid through the oppositeends of said valve chamber past the remote sides of said valve flangesto said supply passages.

8. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, fluid distributing valves reciprocably mounted insaid valve chamber, said valves movable into and out of abuttingrelation, one valve controlling the flow of pressure fluid to one end ofsaid cylinder bore and the other valve controlling the flow of pressurefluid to the other end of the cylinder bore, means for effectingmovement of said valves relative to one another into their differentnormal operating positions in said valve chamber, a pressure fluidsupply, means cooperating with said valves respectively for providing ametered flow of pressure fluid from said fluid supply to the oppositeends of said valve chamber and means providing fluid supply passages forconducting pressure fluid from the ends of said valve chamberrespectively to the opposite ends of said cylinder bore, said valvesrespectively controlling the flow of pressure fluid from said fluidsupply through the opposite ends of said valve chamber to said supplypassages.

9. A pressure fluid motor comprising, in combination, a cylinder, apiston therein, and fluid distribution means for the motor includingpassage means for supplying operating fluid to the opposite ends of thecylinder at the opposite ends of said piston respectively, an operatingfluid supply, valve means including a pair of cooperating, relativelymovable, valve elements movable into abutting relation and respectivelycontrolling the flow of operating fluid to the opposite ends of saidcylinder, for controlling the communication of said passage means withthe fluid supply, and means cooperating with said valve elements forproviding metered flow of operating fluid to the opposite ends of thecylinder, said valve elements of said valve means in certain positionsthereof momentarily concurrently completely cutting 01f communication ofboth of said passage means with said fluid supply.

10. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, fluid distributing valves movably mounted in saidvalve chamber, means for effecting movement of said valves rela tive toone another into their diiferent normal operating positions in saidvalve chamber, means cooperating with said valves providing an inberthrough the opposite ends of said valve cham-' her to said supplypassages.

11. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, cooperating, relativelymovable, fluid distributing valves movably mounted in said valvechamber, said valves being guided solely at their exterior peripheriesand having inwardly directed flanges, means for effecting movement ofsaid valves relative to one another into their different normaloperating positions in said valve chamber, means cooperating with saidvalves providing an internal fluid supply chamber within-the valves,means cooperating with said inwardly directed valve flanges forproviding a metered flow of pressure :fluid from said fluid supplychamberto the Opposite ends of said valve chamber, and means providingfluid supply passages connecting the opposite ends of said valve chamber'at the remote sides of said valves respectively to the opposite ends ofsaid cylinder bore, said valves respectively controlling the flow ofpressure fluid from said fluid supply chamber past saidm'etering-providing means and through the opposite ends of said valvechamber to said supply passages.

12. In a pressure fluid motor, the combination comprising a cylinder"having a bore, a piston re- 40 ciprocable in said cylinder bore, andfluid distribution means for supplying pressure fluid to and exhaustingfluid from said cylinder bore to effect reciprocationof said pistoncomprising means providing a valve chamber having a uniform bore andvalveseat surfaces at its opposite ends, a

pair of coaxial, relatively movable, fluid distributing valvesreciprocably mounted'in said valve chamber, said valves havingsleeve-like'body portions and external flanges surrounding said bodyportions and slidingly fitting said valve chamber bore, said sleeve-likebody portions of said valves at their remote ends "having valve seatingsurfaces. respectively adapted "to seat against said valve seatsurfaces, means for effecting movement of said valves relative to oneanother'into their different normal operating positions in said valvechamber, and means providing fluid supply passages leading from theopposite ends of said valve chamber respectively to the opposite ends ofsaid cylinder bore,.said valves respectively controlling the flow ofpressure fluid through the opposite ends of said valve chambertosaidsupply passages.

13. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in .said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom saidcylinder bore to effect reciprocation of said piston comprisingmeans providing a valve chamber having'a uniform bore and valve seatsurfaces at its opposite ends, a pair of coaxial, relatively movable,fluid distributing valves movable into and out of abutting engagementand reciprocably mounted in said valve chamber, said valves havingsleeve-like body portions and external flanges surrounding said bodyportions and slidingly fitting said valve chamber bore, said sleeve-likebody portions of said valves at their remote ends having valve seatingisurfaces respectively adapted to seat ing movement of said valvesrelative to one another into their different normal operatingposiagainst said valve seat surfaces, means for effecttions in saidvalve-chamber, and'means providing fluid supply passages leading fromthe opposite ends of said valve chamber respectively to the oppositeends of said cylinder bore, said valves respectively controlling theflow of pressure fluid through the opposite ends of said valve chamberto said supply passages.

14. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, cooperating, relativelymovable, fluid distributing valves reciprocably mounted in said Valvechamber, means for eflecting movement of said valves relative to oneanother into their different normal operating positions in said valvechamber, means cooperating With said valves respectively providingmetering spaces through which fluid must flow to the opposite ends ofsaid valve chamber, and means providing fluid supply passages forconnecting the opposite ends of said valve chamber respectively with theopposite" ends of said cylinder bore, said valves respectivelycontrolling the flow of fluid past said metering spaces and through theopposite ends of said valve'chamber tosaid supply passages.

15. In a pressure fluid motor, the combination comprising acylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fl-uidfrom said cylinder bore to eiTect reciprocation of said pistoncomprising means providinga valve chamber, cooperating, relative- 1ymovable, fluid distributing valves mounted in said valve chamber andreciprocably guided in said valve chamber solely at their exteriorperipheries, said valves having internal bores, means foreffectingmovement of said valves relative to one another into theirdifferent normal operating positions in said valve chamber, meansincluding portions projecting within said valve bores respectively .formetering "the flow of fluid past saidvalves to the opposite ends of saidvalve chamber, and means providing fluid supply passages for connectingthe opposite ends of said valve chamber respectively to the oppositeends of said cylinder bore, said valves respectively controlling theflow of pressure fluid past said flowmetering means and through theopposite ends of said valve chamber to said supply passages.

16. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to efiect reciprocation of said pistoncomprising means providing a valve chamber, cooperating, relativelymovable, fluid distributing valves reciprocably mounted in said valvechamber, means for effecting movement of said valves relative to oneanother into their diflerent normal operating positions in said valvechamber, means cooperating with said valves respectively providingmetering spaces through whichfluid must flowftothe opposite ends of saidvalve chamber, and means providing fluid supply passages for conductingpressure fluid from the opposite ends of said valve chamber respectivelyto the opposite ends of said cylinder bore, said valves respectivelycontrolling the flow of pressure fluid through said metering spaces andthrough the opposite ends of said valve chamber to said supply passages,and said valves when in certain positions in said valve chambermomentarily completely cutting off the flow of pressure fluid throughboth metering spaces to said valve chamber ends.

17. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, cooperating, relativelymovable, fluid distributing valves reciprocably mounted in said valvechamber, said valves arranged in coaxial relation and movable into andout of abutting relation, means for effecting movement of said valvesrelative to one another into their diiferent normal operating positionsin said valve chamber, means cooperating with said valves respectivelyproviding metering spaces through which fluid must flow to the oppositeends of said valve chamber, and means providing fluid supply passagesfor conducting pressure fluid from the opposite ends of said valvechamber respectively to the opposite ends of said cylinder bore, saidvalves respectively controlling the flow of pressure fluid through saidmetering spaces and through the opposite ends of said valve chamber tosaid supply passages, and said valves in certain positions thereof insaid valve chamber momentarily completely cutting off the flow ofpressure fluid through both metering spaces to said valve chamber ends.

18. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to eflect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, annular fluid distributing valves, said valvesarranged in coaxial relation and reciprocably mounted in said valvechamber, said valves dividing said valve chamber into inner and outerpressure spaces and end pressure spaces at the remote ends of saidvalves, means for effecting movement of said valves relative to oneanother into their different normal operating positions in said valvechamber, means for supplying motive pressure fluid to one of said innerand outer {pressure spaces, said jvalvemovement-effecting meansincluding means for supplying pressure fluid to and exhausting fluidfrom said other of said inner and outer pressure spaces for effectingmovement of said valves into certain of their operating positions, meansproviding fluid supply passages for connecting said end pressure spacesrespectively with the opposite ends of said cylinder bore, said valvesrespectively controlling the flow of pressure fluid from the motivepressure fluid supply space through said end pressure spaces to saidsupply passages.

19. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddis tribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to efiect reciprocation of said pistoncomprising means providing a valve chamber, a pair ofcooperatingrelatively movable, annular fluid distributing valves, saidvalves arranged in coaxial relation and reciprocably mounted in saidvalve chamber, said valves movable into and out of abutting relation,said valves dividing said valve chamber into inner and outer pressurespaces and end pressure spaces at the remote ends of said valves, meansfor effecting movement of said valves relative to one another into theirdifferent normal operating positions in said valve chamber, means forsupplying motive pressure fluid to one of said inner and outer pressurespaces, said valve-movement-effecting means including means forsupplying pressure fluid to and exhausting fluid from saidother of saidinner and outer pressure spaces for effecting movement of said valvesinto certain of their operating positions, and means providing fluidsupply passages for connecting said end pressure spaces respectivelywith the opposite ends of said cylinder bore, said valves respectivelycontrolling the flow of pressure fluid from the motive pressure fluidsupply space through said end pressure spaces to said supply passages.

20. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperatingrelatively movable, annular, fluid distributing valves, said valveshaving telescopic sliding engagement and movable into and out ofabutting relation, said valves arranged in coaxial relation andreciprocably mounted in said valve chamber, said valves-dividing saidvalve chamber into inner and outer pressure spaces and end pressurespaces at the remote ends of said valves, means for effecting movementof said valves relative to one another into their different normaloperating positions in said valve chamber, means for supplying motivepressure fluid to one of said inner and outer pressure spaces, saidvalve-movement-effecting means including means for supplying pressurefluid to and exhausting fluid from said other of said inner and outerpressure spaces for effecting movement of said valves into certain oftheir operating positions, and means providing fluid supply passages forconnecting said end pressure spaces respectively with the opposite endsof said cylinder bore, said valves respectively controlling the flow ofpressure .fluid from the motive pressure fluid supply space through saidend pressure spaces to said supply passages.

21. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, fluid distributing valves reciprocably mounted insaid valve chamber, said valves being hollow, means for effectingmovement of said valves relative to one another into their differentnormal operating positions in said valve chamber, means includingportions projecting in opposite directions from the opposite ends ofsaid valve chamber within said hollow valves respectively, for providingmetered flow of fluid past said-valves to the opposite ends of saidvalve chamber, and means providing fluid supply passages for connectingthe opposite en of said valve chamber respectively to the 0pposite endsof said cylinder bore, said valves re spectively controlling the flow ofpressure fluid past said metering-providing means and through theopposite ends of said valve chamber to said supply passages.

22. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber, a pair of cooperating,relatively movable, fluid distributing valves reciprocably mounted insaid valve chamber, said valves each having a sleeve-like body portionand an annular flange surrounding the body portion, said externalannular flanges slidinglyfitting portionsof the valve chamber, means foreifecting movement of said valves relative to one another into theirdifferent normal operating positions in said valve chamber, meansincluding portions projecting in opposite directions from the oppositeends of said valve chamber within the sleeve-like body portions of saidvalves respectively, for providing a metered flow o-f pressure fluidpast said valves to the ends of said valve chamber, and means providingfluid supply passages for connecting the opposite ends of said valvechamber respectively to the opposite ends of said cylinder bore, saidvalves respectively controlling the flow of pressure fluid past saidmetering-providing means and through the opposite ends of said valvechamber to said supply passages.

23. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chamber having valve seat surfaces atits opposite ends, a pair of cooperating, relatively movable, fluiddistributing valves reciprocably mounted in said valve chamber, saidvalves each having a sleeve-like body portion and an annular flangesurrounding the body portion, said external annular flanges slidinglyfitting portions of said valve chamber, the remote ends of saidsleeve-like body portions of said valves having annular valve seatingsurfaces respectively adapted to seat against said valve seat surfacesat, the ends of said valve chamber, means for efiecting movement of saidvalves relative to one another into their difierentnormal operatingpositions in said valve chamber, means projecting in opposite directionsfrom the opposite ends of said valve chamber within the sleeve-like bodyportions of said valves respectively and cooperating with said valvesfor providing a metered flow of pressure fluid past said valves to theends of said valve chamber, and means providing fluid supply passagesfor connecting the opposite ends of said valve chamber respectively tothe opposite ends of said cylinder bore, said valves respectivelycontrolling the flow of pressure fluid past said metering-providingmeans and through the opposite. ends of said valve chamber to saidsupply passages.-

24. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocable in said cylinder bore, and fluiddisoperating, relatively movable, fluid distributing valves movablymounted in said valve chamber, said valves arranged in coaxial relationand being hollow, one valve controlling the fluid supply solely to oneend of said cylinder bore and the other valve controlling the fluidsupply solely to the opposite end of said cylinder bore, and thepressure fluid flowing to one end of said cylinder bore through both ofsaid hollow valves, means .for effecting movement of said valves,relative to one another into their difierent normal operating-positionsin said valve chamber, and means providing fluid supply passages leadingfrom the opposite ends of said valve chamber respectively to theopposite ends of said cylinder bore, said valves-respectivelycontrolling the flow of pressure fluid through the ends of said valvechamber to said supply passages.

25. A pressure fluid motor comprising, in combination, a cylinder, apiston therein, and fluid distribution means for the motor includingpassage means forsupplying operating fluid to the opposite ends of thecylinder at the opposite ends of the piston respectively, an operatingfluid supply, valve means including apair of cooperating, relativelymovable valve elements each movable into -a position in which it exertsa pressure to hold the other stationary and respectively controlling theflow of operating fluid to the opjecting saidvalve elements to valvethrowing pres-sures to move said valve elements into their differentoperating positions, said valve throwing means including surfaces onsaid valve elements subjected by fluid flowing past said valve elementswhen the latter are in open position to pressures tending to close saidvalve elements, one of said valve elements when open exerting a pressurewhich holds the other in closed position, and said valve elements incertain positions thereof momentarily concurrently completely cuttingoff communication of both of said passage means with said fluid supply.

26. A pressure fluid motor comprising, in combination, a cylinder, apiston therein, and fluid distribution means for the motor includingpa'ssage means for supplying operating fluid to the opposite ends of thecylinder at the opposite ends of theipiston respectively, an operatingfluid supply, valve means including a pair of cooperating, relativelymovable valve elements movable into abutting engagement and respectivelycontrolling the flow of operating fluid to the opposite ends of saidcylinder, for controlling the communication of said passage means withsaid fluid supply, andvalve throwing meansfor subjecting said; valveelements to valve throwing pressures towmove said valve elements intotheir different operating positions, said valve throwing means includingportions on at least one of said valve elements subjected by fluidflowing past said valve element to the cylinder, to a force tending tosweep said valve element to its closed position, one of said valveelements being held in closed position by the other valve elementabuttingly acting thereon and said valve elements in certain positionswhen they are out of abutting engagement momentarily concurrentlycompletely'cutting off communication of both of said passage means withsaid fluid supply.

27. A pressure fluid motor comprising, in combination, a cylinder, apiston therein, and fluid distribution. meansfor the motor includingpas+ sage means for supplying operating fluidto the opposite ends of:the cylinder atthe oppositeends of the piston respectively, anoperating fluid supply, valve means including a pair ofcooperating,-:relatively 1 movable valve elements re spectivelycontrolling the flow of operating fluid to the opposite ends of saidcylinder, for'c'ontrollingthe communication oflsaid passage means withsaid fluid supply, and valve throwing'means for subjecting said valveelements to valve throw ing pressures to move said valve elements'intotheir different operating positions including means for subjecting eachvalve element to closing forces respectively-exerted by motive'fluidpassing it on the way to the cylinder and by fluid pressure controlledby the motor piston in its movement, said valve elements being movabletoward and from one another and whenin their remote positionsmomentarilyconcurrently completely cutting off communication of both ofsaid passage meanswith'said fluid supply andeach exerting in its fullopen position a force forholding the other closed.

28. A pressure fluid motor comprising-,- incombination, a cylinder, apiston therein, and fluid distribution meansforthe motorvincludingpassage means for supplying operating' fluid tothe oppositeends of saidcylinder at the opposite ends of said piston respectively, an operatingfluidsupply, valve means including a pair of-cooperating, relativelymovable lvalve elementsmovable into abutting engagement: andrespectively controlling the flow of operating fluid to the oppositeends of said cylinder, for controlling the'communication of said passagemeans withsaid fluid supply, and valve throwing .means ,for, subjectingsaid valve elements to valve throwing pressures to move said valveelements intotheir difierent operating positions, said 'valve elementsbeing movable toward one another into abutting relation and from oneanother out sof -abutting relation and when in their positions away fromone another out of abutting relation momentarily concurrently completelycutting off communication of both of said passage means withsaid fluidsupply, and said valve elements when so completely cutting oficommunication cooperating in forming. a partition extending in thedirection of valve movement and having at one side of said partitionsaid operatingfluid supply andat the other side thereof surfacesintermittently subjectedto pressures to efiect positioning of the valveelements in said non-abutting positions.

'29. A pressure fluid motorcomprisingfincombination, a cylinder, apiston therein-,rand fluid distribution means for the motor "includingED345- sage means for supplying operating fluid to the opposite ends ofthe cylinder at the opposite ends of the piston respectively, anoperating fluid supply, valve means including a pair of cooperating,relatively movable valve elements respectively controlling the flow -'ofoperating 'fluid to the opposite ends ofsaid cylinder forcontrolling'the communication of said passage means with said fluidsupply, and valve throwing means for subjecting said valve elements tovalve throwing pressures to move said valveelements into their differentoperating positions, said valve throwing means including 'for -each ofsaid valve elements means associated with the latter and subjected to avalve 'closing 'pressure-by"'fluid flowing past said valve element tothe cylinder and means subjected toa supplemental valve closing pressurecontrolledzby the position of: the motor/piston, said valveelen'lentstbeing movable toward and from one another, each of saidvalves when in'its full open position exerting a force forholding theother closed, and said valve elements movable to effect concurrentlyinterruption of communication of each of said passage means withsaidfluid supply. 7

- 30. In a pressure fluidmotor,vtheicombination comprising a cylinderhaving a bore, a piston reciprocab-lein said cylinder bore, a valvechest providing a. chamber, fluid distribution passages leading fromsaidvalve chamber to the opposite ends of :said cylinder bore, valve meansin said chamber for -.controlling thelflow of motive fluid from saidchamber to said distribution pass-ages including relatively. movablefluid distributing valve elements,v said .valve elements movable topositions in which. they concurrently interrupt communication, betweensaid chamber and said fluid. distribution passages and simultaneouslycooperate iniprovlding a partition which divides saidlchamberfromend toend .andat one side of which. partition ,bothof saiddistributionpassages openintothe chamber, asource of operating fluidcommunicating.withsaidchamber at a point separated by said partition,whenthe same is .formed, from said ,fluid distribution passages,

and. means for ,movingsaid valvelelements into their-.difierentoperating positionsincluding. passage means ior, delivering.valvelthrowing fluid to said valve elements to .act..upon. the same atthe othervside of said partition. 1

..3l. ,A pressure fluid motor comprising,..in .combination, a cylinder,a. piston-therein, and fluid distribution means for the motor includingpassagemeans for supplying operating fluidto the opposite ends of the.cylinderlat the opposite ends of,thevpiston.respectivelman operatingfluid supply, valve means. including a pair of cooperating,relativelymoving valve elements respectively controlling the flow ,ofoperatinglfiuid to the opposite ends of .said cylinder for controllingthe communication ,ofsaid passage means with said fluidlsupply, andvalve throwing means for subjecting said valve elements. to valve.throwing pressures to move said valve elements into their differentoperating positions including oppositely extending flanges on each ofsaid valve elements respectively.continuouslyand intermittentlysubjectedto valve closing forces whenlsaid valve element is-in openposition, said, valveelements being ,movable toward and from oneanother, each ofsaidvalve'elements when in its full open positionexerting a force for holding the other closed, and said valve elementsmovable to effect concurrently interruption of communication of each ofsaid passage means with said fluid upp y.

'32; A pressure fluid motorcomprising, incombination, a cylinder, apiston therein, and'fluid distribution means for'the motor includingpassage meansfo-rsupplying operating fluid to the opposite ends'of thecylinder at the opposite'ends ofthe'piston respectively, an-operatingfluid supply valve 'means including a--pair of cooperating, relativelymovable valve elements respectively controllingthe' flow of operatingfluid to the opposite ends of said cylinder ior'controlling thecommunication of said passage means with said fluid supply, and valvethrowing means forsubjecting said valve-elements to valve throwingpressures to move said valve elements into their diflerent operatingpositions-including portions on each ofs'aid valveelements-continuouslysubjected by fluid :flowing past said valve elements to the, cylinder tovalve closing forces when said valve elements are in openposition andmeans providing oppositely facing pressure areas intermittentlysubjected to valve closing forces to supplement said first mentionedforces and close said valve elements in alternation, said valve elementsbeing movable toward and from one another, each of said valve elementswhen in its full open position exerting a force for holding the otherclosed, and said valve elements movable to effect concurrentlyinterruption of communication of each of said passage means with saidfluid sup ply.

33. In a pressure fluid motor, the combination comprising a cylinderhaving a bore, a piston reciprocab le in said cylinder bore, and fluiddistribution means for supplying pressure fluid to and exhausting fluidfrom said cylinder bore to effect reciprocation of said pistoncomprising means providing a valve chest, a pair of cooperating,relatively movable, fluid distributing valves movably mounted in saidValve chest for controlling the supply of pressure fluid to the oppositeends of said cylinder bore, said valves arranged in coaxial relation andbeing hollow, and the pressure fluid flowing to the rear end of saidcylinder bore through both of said hollow valves, means for effectingmovement of said valves relative to one another into their diiierentnormal operating positions in said valve chest, and means providingfluid supply passages leading from the opposite ends of said valve chestrespectively to the opposite ends of said cylinder bore, said valvesrespectively controlling the flow of pressure fluid through the ends ofsaid valve chest to said supply passages.

JOHN CLARK CURTIS.

CERTIFICATE OF CORRECTION.

Patent No. 2,22u,859. December 17, 191m, JOHN CLARK CURTIS.

It is hereby certified that error appears in the printed specificationof the above numbered patent requiring correction as follows: Page 5,second column, line M1, for "ls" read is-; page 5, second column, line65- 611., for "pressure" read --pressures; page 8, second column, line714, claim 21,- for "en" read --ends-; page 9, second column, line 10,claim 2h, after the word "valves" strike out the comma; and that thesaid Letters Patent should be read with this correction therein that thesame may conform to the record of the case in the Patent Office.

Signed and sealed this L en day of February, A. D. 19in Henry VanArsdale,

(Seal) Acting Commissioner of Patents.

